DEUTSCH E. R.
- Society of Geomagnetism and Earth, Planetary and Space Sciences
- Journal of geomagnetism and geoelectricity (ISSN:00221392)
- vol.8, no.3, pp.108-117, 1956
An experimental method is described, designed chiefly to furnish data for a study of the direction, and stability with time, of thermoremanence in rocks. Specimens were heated to the Curie point in an evacuated electric furnace. Two pick-up coils were arranged close to the gap of a tuned a. c. electromagnet providing a maximum field <i>H</i> of 2400 oersteds. These were balanced to make their resultant e. m. f. zero in the presence of <i>H</i> alone, and proportional to <i>dI/dt</i> when a specimen of intensity of magnetization <i>I</i> was in the gap. This e. m. f. was applied to the vertical plates of a cathode ray oscilloscope. The potential drop over a small resistance in the electromagnet input was applied to the deflection coils, giving a measure of <i>H</i>. Computations based on the resulting pattern on the c. r. o. screen yield a loop of the <i>I-H</i> type, with <i>I</i> in arbitrary units, from which the coercivity can be evaluated. A pronounced "sawtooth" pattern has been observed in the (<i>dI/dt)-H</i> traces of pyrrhotite and franklinite specimens, particularly just below the respective Curie points.